This is one of the best dramas I have ever watched, It is simply amazing. Besides the lead actors who have scorching chemistry we have a stellar ensemble cast which includes the amazing second leads with contrasting personalities, north korean comrades, Cho cheol Gang, North Korean millitary village ladies, Seo dan's mother and uncle and Captain Ri's father. Each one of them shines in their respective roles. Every scene shot in Switzerland is breath - taking
I loved the first 10 episodes more, They are outstanding ! However in the later episodes some sub plots like Captain Ri and Cho Cheol Gang coming to South Korea by digging a tunnel seem illogical and far fetched. Similarly the way NIS of South Korea warmed up to RiRi couple's love story was a bit too much...also how Captain Ri's father casually kills a very important North korean officer (Director of Millitary to be precise) in an attempt to protect his son is over the top. The actors and story is so good that you tend to overlook gaps like these...
Besides the flawless acting and overall gripping storyline, CLOY has an amazing OST. Make sure you don't miss this one out!